Super-hydrophobic insulating coating with surface microstructure as well as preparation method and application of super-hydrophobic insulating coating

Abstract

The invention belongs to the technical field of surface modification, and particularly relates to a super-hydrophobic insulating coating with a surface microstructure and a preparation method and application of the super-hydrophobic insulating coating. The defects of poor environmental stability, low regulation and control precision, insulation performance attenuation and the like in the prior art are overcome, the static contact angle of the disclosed super-hydrophobic insulation coating is larger than or equal to 150 degrees, the rolling angle is smaller than or equal to 5 degrees, meanwhile, the insulation strength is larger than or equal to 90% of that of an original substrate (the breakdown field strength is larger than or equal to 20 kV / mm), and collaborative optimization of the super-hydrophobic performance and the insulation performance is achieved; moreover, after the coating is naturally aged outdoors for 3 years, the contact angle change rate is smaller than or equal to 10%, the insulation strength attenuation rate is smaller than or equal to 8%, and the long-term environmental stability of the super-hydrophobic insulating coating is effectively improved. A precise regulation and control mechanism is also established based on a molecular dynamics simulation-based low-droplet adhesion microstructure insulation surface design method, so that the droplet contact time is reduced by more than 60% compared with a flat surface, the instantaneous leakage current is reduced by 40%-60%, and the method not only adapts to a polluted environment with the temperature range of-40 DEG C to 180 DEG C and the salt mist concentration of less than or equal to 0.5 mg / m, but also meets the preparation requirements of power equipment with complex shapes.

Description

Technical Field

[0001] This invention belongs to the field of surface modification technology, specifically relating to a superhydrophobic insulating coating with surface microstructure, its preparation method, and its application. Background Technology

[0002] In outdoor or harsh operating environments of power systems and electronic equipment, droplet adhesion to insulating surfaces is a core cause of performance failure. From a microscopic perspective, after droplets (especially those containing contaminants) adhere to the insulating surface, they form localized conductive regions, leading to distortion of the surface electric field—when the droplet conductivity (typically 10⁻⁶) decreases... -4 ~10 - ² S / m) and insulation material (typically 10 - ¹ 4 ~10 - The difference in S / m (¹²) reached 10¹ 0 At high magnitudes, electric field concentration occurs at the edge of the droplet, with local field strength reaching 3 to 5 times the average field strength, making it highly susceptible to partial discharge. Long-term partial discharge can erode the molecular chain structure of insulating materials (such as the oxidative degradation of polyolefin materials), leading to a gradual decrease in insulation strength. When droplets accumulate and bridge electrodes, they can directly form conductive paths, causing flashover accidents and resulting in significant economic losses and safety risks.

[0003] Existing typical accident cases fully demonstrate the harmfulness of this problem: In 2008, during cleaning operations at an air-cooled power plant, sewage droplets adhered to the surface of the A-phase bushing of a standby transformer and formed a continuous water film, causing the leakage current to surge from the normal μA level to the mA level, ultimately triggering a flashover trip and causing the unit to be shut down for 72 hours; In 2009, in a 220 kV substation, due to the high humidity environment, dirt and condensation droplets combined on the external insulation surface of the 10 kV switchgear, forming a conductive layer and causing a grounding fault, resulting in the shutdown of the No. 3 main transformer and affecting the power supply to 12,000 households in the surrounding area. According to statistics from the power industry, insulation faults in humid and polluted environments account for 63% of all faults, of which 85% are directly related to droplet adhesion.

[0004] To address this problem, existing technologies mainly fall into two categories, but both have significant limitations: 1. Low surface energy coating technology: This technology reduces droplet adhesion by coating with low surface energy materials such as polytetrafluoroethylene (PTFE) and fluorocarbon resin (surface energy ≤ 20 mN / m). However, this technology has three major bottlenecks: First, poor environmental stability—outdoor ultraviolet radiation (wavelength 200~400 nm) causes the fluorocarbon bond to break, and after 3 years, the surface energy rises to over 35 mN / m, resulting in loss of hydrophobicity; second, insufficient adaptability to extreme environments—in high-temperature (≥ 150 ℃) or highly corrosive environments (such as marine salt spray), the coating is prone to aging and peeling off, and the peeled area easily forms an "island effect," which in turn exacerbates droplet aggregation; third, poor process compatibility—it requires extremely high surface flatness of the substrate (roughness Ra ≤ 0.1 μm), making it difficult to apply to complex-shaped power equipment components.

[0005] 2. Macroscopic Roughening Treatment: Micrometer-level (1~10 μm) rough structures are constructed through processes such as sandblasting and etching. An air cushion is formed using the "Cassie-Baxter" model to reduce the contact area of ​​droplets. The core drawbacks of this technology are: First, it is highly sensitive to contamination—micrometer-level trenches easily accumulate contaminants such as dust and salt, and the contact angle drops from 150° to below 100° after 3 months; second, it reduces mechanical strength—the rough structure reduces the tensile strength of the substrate by 15%~20%, posing a risk of breakage in scenarios such as high-voltage insulators subjected to mechanical loads; third, it lacks microscopic control—the size and distribution of the structure cannot be precisely controlled, and the droplet rebound rate is only 40%~50%, making it difficult to achieve efficient desorption.

[0006] Furthermore, existing studies have largely limited the application of molecular dynamics simulations to qualitative analysis of single microstructures (such as columnar structures), failing to establish a quantitative correlation model between "microstructure parameters, droplet dynamics, and insulation performance," and failing to discover the key low-contact-time mode of ring bounce. This results in a disconnect between simulation results and engineering applications, making it difficult to guide actual design. Summary of the Invention

[0007] In view of this, in order to solve the key technical problems of insulation performance degradation and increased risk of leakage and flashover caused by droplet adhesion on traditional insulating surfaces in complex environments such as humidity, fog, and condensation, this invention uses molecular dynamics simulation as the core technology to overcome the limitations of traditional macroscopic experiments in accurately controlling nanoscale microstructures. By constructing an atomic-level droplet-insulating surface interaction system, it achieves visualized tracking and mechanistic analysis of interface behavior, and then establishes a quantitative correlation model of "microstructure size-droplet spreading behavior-adhesion performance", thereby obtaining a superhydrophobic insulating coating with surface microstructure based on the above model, as well as its preparation method and application.

[0008] The first objective of this invention is to provide a superhydrophobic insulating coating with a surface microstructure. To achieve the above objective, this invention employs the following technical solution: A superhydrophobic insulating coating with surface microstructure includes a superhydrophobic insulating substrate and microstructures modified on the surface of the superhydrophobic insulating substrate; the microstructures are one or more of the following: spherical microstructures with a diameter of 2-20 nm, grooved microstructures with a bottom length of 2-10 nm, or conical microstructures with a bottom diameter of 4-20 nm.

[0009] The superhydrophobic insulating matrix of the present invention includes one or more of polytetrafluoroethylene, epoxy resin, and polystyrene.

[0010] Furthermore, the spacing between the microstructures is less than 0.5 times the maximum spreading diameter of the droplets on the flat surface of the superhydrophobic insulating substrate; the droplets are nanoscale droplets with a diameter of 10-100 nm.

[0011] Furthermore, the spacing of the microstructures is 10-100 nm.

[0012] Furthermore, the overall thickness of the coating is 50-200 nm, wherein the ratio of the height of the microstructure to the thickness of the superhydrophobic insulating substrate is 1:3-1:12.5.

[0013] Furthermore, the groove depth of the groove microstructure is 2-6 nm, the groove width is 2-10 nm, and the cone tip angle of the conical microstructure is 30°-120°.

[0014] It is worth noting that, in order to overcome the shortcomings of existing technologies such as poor environmental stability, low control precision, and insulation performance degradation, this invention adopts a low-droplet-attachment microstructure insulating surface design method based on molecular dynamics simulation. It selects three nanoscale microstructures—spherical, conical, and grooved—as the core modification units for the superhydrophobic insulating surface, wherein: Spherical microstructures: diameter 2~20nm, spacing <0.5 times the maximum spreading diameter of the droplet on the flat surface ( D max Design basis: The size ratio of the 2~20nm range to the 10nm standard droplet is 0.2~2.0. D 1) It can effectively control the "piercing effect" during droplet spreading; the spacing design ensures that the droplet will inevitably come into contact with at least 3 microstructures when it impacts, avoiding rebound failure caused by "suspended contact".

[0015] Conical microstructures: base diameter 4~20nm, tip angle 30°~120°, spacing the same as spherical microstructures. Design rationale: the tip angle affects the rebound mode by changing the retraction rate of the droplet contact line; the 30°~120° range can cover the contact line diffusion rate (0.5~2nm / ps) required for annular rebound; the base diameter is consistent with that of the spherical microstructures to facilitate comparison of the control effects of different morphologies.

[0016] Groove microstructure: bottom surface length 2~10nm, groove depth 2~6nm, spacing the same as spherical microstructure. Design basis: bottom surface length and droplet radius form a size ratio of 0.2~1.0 (…). D 2) The ratio of groove depth to length is 0.2~0.6, which can maximize the capture of air to form a stable gas film (gas film thickness ≥0.5nm) and assist the rapid retraction of droplets.

[0017] The superhydrophobic insulating coating with surface microstructure disclosed in this invention is modified with one or more composite microstructures. All of these microstructures are chemically bonded to the superhydrophobic insulating substrate, with a bonding strength ≥5 MPa, preventing structural detachment under environmental loads.

[0018] A second objective of this invention is to provide a method for preparing the superhydrophobic insulating coating with surface microstructure as described above. To achieve the above objective, this invention employs the following technical solution: A method for preparing a superhydrophobic insulating coating with surface microstructure includes the following steps: (1) An initial molecular dynamics simulation system was constructed using nanoscale droplets with a diameter of 10-100 nm and an insulating matrix with one or more microstructure prototypes such as spheres, grooves or cones pre-modified on the surface. The interatomic interactions were defined using the Lennard-Jones force field. (2) Set the droplet impact velocity to 1-12 Åm / ps, simulate the impact process of nanodroplets on the microstructure surface within this velocity range, and record the curves of spreading diameter and contact angle changing with time; (3) Change the characteristic size of each microstructure and measure the ratio of the size of each microstructure to the droplet diameter. D Simulate different D Impact process under certain conditions; the ratio D include D 1. D 2. D 3, of which D 1 represents the ratio of the diameter of the spherical microstructure to the diameter of the droplet. D 2 represents the length of the bottom surface of the groove microstructure divided by the droplet radius. D 3 represents the ratio of the bottom diameter of the conical microstructure to the droplet diameter; (4) Based on the droplet bounce mode under the microstructure, the droplet with the best hydrophobicity was preliminarily screened. D Value range; the preferred rebound modes of this invention include complete rebound, partial rebound, and adhesion; (5) For different D The droplet dynamics behavior under the specified value was quantitatively analyzed, the contact time between the droplet and the coating surface was calculated, and the contact time was compared with that of the droplet impacting the flat surface of the superhydrophobic insulating substrate. (6) Select the droplet with the shortest contact time and the complete bounce mode. D The value is used as the optimal size parameter. The maximum spreading diameter when nanoscale droplets impact a flat surface is used as the benchmark to determine the microstructure spacing, so that the spacing is <0.5 times the maximum spreading diameter. (7) Based on the simulation optimization parameters, the target microstructure is prepared on the surface of the superhydrophobic insulating substrate by nanoimprinting or vapor deposition to obtain the superhydrophobic insulating coating.

[0019] Preferably, in step (7), the temperature of nanoimprinting is 80-120 ℃, the pressure is 10-30 MPa, and the holding time is 5-15 min, while the deposition rate of vapor deposition is 0.5-2 nm / min and the deposition temperature is 50-100 ℃.

[0020] More preferably, step (7) further includes post-treatment, which involves placing the prepared coating in a vacuum oven and holding it at 60-80°C for 2-4 hours to remove residual stress. Furthermore, in step (1), the initial molecular dynamics simulation system is controlled at 25°C, the pressure is controlled at standard atmospheric pressure, and the simulation time step is 2 fs.

[0021] Preferably, in some embodiments, the simulation system is constructed with a 10 nm diameter droplet (MW water molecule model, containing ~5500 water molecules) and a substrate modified with the target microstructure as the core, and the simulation box size is set to 100×100×50 nm³, the temperature to 25 ℃, and the time step to 2 fs.

[0022] Furthermore, in step (3) D 1. D 2. D The adjustment range for value 3 is 0.2-2.0, and the adjustment gradient is 0.1. When the simulation shows the liquid film rapidly contracting and detaching from the surface, the corresponding value is recorded. D The value is used as the preferred parameter.

[0023] Preferably, in some embodiments, the multi-condition impact simulation is performed by changing the impact Weber number ( We =1.5-217.5, corresponding to impact velocities of 1~12 Åm / ps) and microstructure size ratio ( D 1. D 2. D (3=0.2~2.0, adjust gradient 0.1) to simulate the entire process of droplet from impact to rebound, and record key indicators such as spreading diameter, contact angle, and contact time.

[0024] Furthermore, in step (5), the contact time is calculated by taking the time difference from the first contact of the droplet with the surface to the complete detachment from the surface, and the average value is taken from multiple simulations, with the error controlled within ±5%.

[0025] Preferably, in some embodiments, the method for screening the rebound mode is as follows: based on the simulation results, top rebound (no reduction in contact time), annular deposition (droplet residue), and splash rebound (sub-droplet attachment) are excluded, and annular rebound is locked as the optimal mode—in this mode, when the droplet spreads to its maximum diameter, the microstructure pierces the liquid film to form an annular shape, and the surface energy is quickly converted into kinetic energy (conversion efficiency ≥60%), with the shortest contact time.

[0026] In this invention, the determined optimal parameters are: when D 1. D 2. D 3 = 0.2~1.0 and We At a temperature of 80-120°C, all three microstructures exhibited stable annular rebound; combined with contact time data (spherical 35 ps, groove 32 ps, cone 33 ps), the groove microstructure was determined to be ( D The optimal single system is 2=0.6, length 3 nm, groove depth 2 nm, and the optimal composite system is spherical + conical composite structure (volume ratio 1:1).

[0027] It is worth noting that this invention employs molecular dynamics simulations to deeply investigate the interaction process between droplets and surfaces under different microstructure sizes and impact Weber numbers. During the simulation, atomic models incorporating the microstructured surface and the droplet are constructed. The atomic model of the microstructured surface is precisely constructed based on the three microstructures designed above, ensuring that the interaction potential between atoms accurately reflects the physical properties of the microstructure. The droplet is simulated using a suitable water molecule model, considering the hydrogen bonding interactions between water molecules and the interactions between water molecules and atoms on the microstructured surface. The entire process of the droplet from impacting the surface to bouncing away is simulated. During the simulation, the droplet's trajectory is precisely recorded, including its spreading, retraction, and final bounce pattern on the surface. Simultaneously, the contact time between the droplet and the surface is measured in detail, from the initial contact until the droplet completely leaves the surface, ensuring the accuracy and reliability of the measurements.

[0028] A third objective of this invention is to provide an application of the superhydrophobic insulating coating with surface microstructure described above. To achieve the above objectives, this invention employs the following technical solution: Application of a superhydrophobic insulating coating with surface microstructure in improving the surface insulation performance of electrical equipment.

[0029] Preferably, the electrical equipment includes an insulated bucket truck for high-voltage transmission line aerial work, an insulating component for offshore wind power equipment, or an insulating layer for electronic device packaging. The application environment of the superhydrophobic insulating coating with surface microstructure can be a humid environment with a relative humidity ≥60% or an environment with a salt spray concentration ≥0.1 mg / m³. In use, the breakdown field strength of the coating is ≥20kV / mm, and the insulation strength decrease compared to a flat surface insulating substrate is ≤10%.

[0030] Preferably, the superhydrophobic insulating coating with surface microstructure disclosed in this invention can be applied to: High-voltage power equipment: 110 kV~1000 kV transmission line insulators, transformer bushings, GIS basin insulators, etc., to reduce the risk of flashover in humid and polluted environments; New energy equipment: insulating coatings for offshore wind turbine blades, photovoltaic inverter housings, and insulating coatings for the surface of the cargo box of high-altitude insulated bucket trucks, etc., to improve adaptability to extreme environments; In the field of electronic packaging: high-density integrated circuit packaging substrates, LED heat dissipation insulation layers, etc., to prevent short circuit faults caused by condensation.

[0031] Therefore, this invention aims to solve key technical problems such as the attenuation of insulation performance and the increased risk of leakage and flashover caused by droplet adhesion on the surface of traditional insulation in complex environments such as humidity, fog, and condensation, and provides a new technical path for the precise design of high-performance insulation materials.

[0032] This invention, supported by molecular dynamics simulation, overcomes the limitations of traditional macroscopic experiments in precisely controlling nanoscale microstructures. By constructing an atomic-level droplet-insulating surface interaction system, it achieves visualized tracking and mechanistic analysis of interface behavior. Specifically, the simulation system is first precisely constructed: an insulating substrate with excellent superhydrophobic properties is selected as the base material, and three characteristic microstructures—spherical, grooved, and conical—are modified on its surface to form a multi-morphological composite micro-nano interface system. Simultaneously, the key parameters of the impacting droplet are fixed, with the droplet diameter set to 10 nm and kept constant. This size not only meets the typical requirements of nanoscale interface interaction research but also accurately maps the adhesion behavior of macroscopic droplets on the microstructure surface.

[0033] The core innovation of this invention lies in establishing a quantitative correlation model of "microstructure size - droplet spreading behavior - adhesion performance." Its key feature is the systematic control of key dimensional parameters of three microstructures to achieve performance optimization: for spherical microstructures, the focus is on adjusting the sphere diameter (2-20 nm range) and the distance between the centers (10-100 nm range); for grooved microstructures, the groove depth (2-6 nm), groove width (2-10 nm), and groove spacing (10-100 nm) are precisely controlled; for conical microstructures, the focus is on the cone height (4-20 nm), cone base diameter (4-20 nm), and cone tip angle (30°-120°). During the simulation, classical molecular force fields are used to describe interatomic interactions. Molecular dynamics simulation software is used to track the dynamic evolution of droplets after impacting the surface, and key indicators such as spreading diameter, contact angle changes, interfacial binding energy, and molecular diffusion coefficient are monitored in real time. The system analyzes the regulatory mechanisms of different microstructure morphologies and sizes on droplet spreading, contraction, and bouncing behaviors. Compared with traditional experimental trial-and-error methods, this invention leverages the unique advantages of molecular dynamics simulation to achieve a dual improvement in design efficiency and accuracy: on the one hand, the simulation allows direct observation of the interaction details between droplet molecules and microstructure surface atoms at the atomic scale, clearly revealing the interfacial adhesion mechanism under the coupling of multiple forces such as van der Waals forces, hydrogen bonds, and surface tension, providing direct mechanistic support for microstructure optimization; on the other hand, parameterized simulation can quickly screen the optimal microstructure combination, avoiding the iterative "preparation-testing-improvement" process in traditional experiments, significantly shortening the R&D cycle and reducing R&D costs. Experimental verification shows that the microstructured insulating surface designed using this method reduces droplet contact time by more than 60% compared to traditional smooth insulating surfaces, while maintaining excellent insulation strength (breakdown field strength ≥20kV / mm). This design method has extremely broad application prospects in the field of electrical insulation technology and can be directly applied to critical scenarios such as high-voltage transmission line insulators, insulating components of offshore wind power equipment, housings of rail transit electrical cabinets, and insulating layers for electronic device packaging. It is particularly suitable for insulation protection in harsh environments such as high humidity, high salt spray, and high condensation, providing important technical support for improving the operational reliability of electrical equipment.

[0034] Compared with the prior art, the advantages of the present invention are: 1. Synergistic improvement in insulation performance and hydrophobicity: The annular rebound mode reduces the droplet contact time from 51 ps on a flat surface to 32-35 ps, a reduction of 31%-37%; the instantaneous leakage current is reduced from 120 μA to below 48 μA, a reduction of more than 60%; the insulation strength is maintained at 22-25 kV / mm, which is 92%-104% of the original substrate, solving the strength attenuation problem caused by traditional roughening.

[0035] 2. Significantly enhanced long-term environmental stability: The nanoscale microstructure does not easily accumulate pollutants, and the contact angle still reaches 138°~145° after 3 years of outdoor aging, with an insulation strength attenuation rate of only 5%~7%; the chemically bonded microstructure bonding method ensures that the coating does not peel off after 100 cycles at -40 ℃~180 ℃, making it suitable for extreme environmental requirements.

[0036] 3. Significantly improved design efficiency and accuracy: Molecular dynamics simulations shorten the parameter screening cycle from 6-12 months in traditional experiments to 2-3 weeks, and increase the hit rate of optimal parameters from 30% to 90%; the simulation accuracy of 0.1 nm ensures a precise match between microstructure size and droplet dynamic behavior.

[0037] 4. Strong process compatibility: The composite preparation process can be adapted to various substrate shapes such as planar, curved, and irregular shapes. The preparation cost is reduced by 60% compared with electron beam lithography, making it suitable for mass production of power equipment such as high-voltage insulators and switch cabinet housings. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 The diagram shows the initial simulation system of this invention (taking a groove microstructure as an example), with the droplet size (10 nm), microstructure parameters (length 3 nm, groove depth 2 nm) and simulation box boundary marked.

[0040] Figure 2 For the three microstructures of the present invention in different We Snapshot of the rebound pattern at that time ( We =1.51~217.5), from top to bottom are standard rebound, ring rebound, and splash rebound.

[0041] Figure 3 This invention relates to droplet impact on a flat surface and three microstructured surfaces (ring-shaped bounce mode). We A snapshot comparing the dynamic spreading process and contact time of (96.64) is taken, with key time points marked (time of maximum spreading diameter, time of initial rebound, and time of complete detachment).

[0042] Figure 4 When the droplet impact groove microstructure of the present invention is used We ~ D Phase 2 diagram, clearly defining the annular rebound region ( D 2 = 0.4~1.0, We=80~120), splash rebound area ( We >120). Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0045] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0046] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0047] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0048] This invention belongs to the field of surface modification technology, specifically relating to a superhydrophobic insulating coating with a surface microstructure, its preparation method, and its application. This invention overcomes the shortcomings of existing technologies, such as poor environmental stability, low control precision, and insulation performance degradation. The disclosed superhydrophobic insulating coating has a static contact angle ≥150° and a roll-off angle ≤5°, while its insulation strength is ≥90% of the original substrate (breakdown field strength ≥20 kV / mm), achieving synergistic optimization of superhydrophobic and insulation performance. Furthermore, after 3 years of natural outdoor aging, the contact angle change rate is ≤10%, and the insulation strength degradation rate is ≤8%, effectively improving the long-term environmental stability of the superhydrophobic insulating coating. This invention also establishes a precise control mechanism based on a molecular dynamics simulation-based low-droplet-attachment microstructure insulating surface design method, reducing droplet contact time by more than 60% compared to flat surfaces and instantaneous leakage current by 40%~60%. This not only adapts to a temperature range of -40℃~180℃ and a polluted environment with salt spray concentration ≤0.5mg / m³, but also meets the fabrication requirements of complex-shaped power equipment.

[0049] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0050] Example 1: Superhydrophobic insulating coating with a single microstructure and its preparation 1. Substrate selection and pretreatment: Modified polytetrafluoroethylene with a thickness of 1 mm was selected as the substrate (breakdown field strength 24 kV / mm, surface energy 18 mN / m). It was ultrasonically cleaned with acetone and deionized water for 30 min each, dried with nitrogen, and then plasma activated (power 100 W, oxygen atmosphere, time 5 min). The surface hydroxyl density was measured to be 6.2 hydroxyl groups / nm².

[0051] 2. Determination of Microstructure Parameters: Based on molecular dynamics simulation results, the optimal single microstructure parameters were selected: groove length 3 nm, groove depth 2 nm, and spacing 12 nm (≤0.5 times). D max =25 nm); spherical microstructures have a diameter of 6 nm and a spacing of 12 nm; conical microstructures have a base diameter of 6 nm, a cone tip angle of 60°, and a spacing of 12 nm.

[0052] 3. Preparation process: The microstructure was formed by nanoimprint lithography (the imprint mold was prepared by electron beam lithography with a precision of 0.1 nm; the imprint temperature was 100 ℃, the pressure was 20 MPa, and the holding time was 10 min); then, a perfluorooctyltrichlorosilane coating was coated by vapor deposition (deposition rate 1 nm / min, temperature 80 ℃, thickness 8 nm); finally, the microstructure was dried in a vacuum oven at 80 ℃ for 3 h to remove residual stress.

[0053] The performance of coatings with three microstructures—grooved, spherical, and conical—was tested, and the results are shown in Table 1. It can be seen that the coating with the microstructure exhibits higher hydrophobicity, reduced contact time (meaning droplets detach more easily from the surface), and stronger anti-aging properties.

[0054] Table 1 Performance indicators of three microstructure coatings

[0055] Example 2: Composite microstructure superhydrophobic insulating coating and its preparation 1. Methods for selecting microstructure dimensions: (1) Simulate the impact process of nanodroplets on the composite microstructure at different impact velocities and analyze its rebound mode; (2) The size of the composite microstructure was changed to simulate different D 1. D Impact process under 3 values, analysis of different D 1. D The impact of three conditions on the rebound outcome; (3) Based on the simulation results under different initial conditions, the impact results are classified into top rebound, standard rebound, annular deposition, annular rebound and splash rebound according to the rebound mode of the droplets; (4) Change the size of the composite microstructure to simulate droplets at different impact velocities and different... D 1. D The impact process under three conditions was used to eliminate microstructures that increased contact time as microstructures for superhydrophobic matrix surface modification. (5) Simulate the process of nanoscale droplet impact step (5) microstructure, for different D 1. D The dynamic behavior under the 3-value was analyzed, and the contact time was compared with that of droplet impact on a flat surface. (6) Analyze the differences in contact time to identify the corresponding ring-shaped rebound. D 1. D The value of 3 determines the size range of each microstructure; the spacing of the composite microstructure is determined by the maximum spreading diameter when nanoscale droplets impact a flat surface, so that the spacing of the composite microstructure is < 0.5 times the maximum spreading diameter; (7) Based on the results of molecular dynamics simulation and theoretical analysis, a superhydrophobic insulating coating with surface microstructure is fabricated.

[0056] 2. Composite Microstructure Design: A composite microstructure consisting of a sphere (6 nm in diameter) and a cone (6 nm in base diameter, 60° at the tip) is employed, with the two microstructures arranged alternately at a spacing of 12 nm and a volume ratio of 1:1. This design combines the stability of the sphere with the guiding properties of the cone to improve rebound efficiency.

[0057] 3. Molecular dynamics simulation verification: A simulation system was constructed using LAMMPS software. A 10 nm droplet was built using the MW water molecule model, and the Lennard-Jones (LJ) force field was used to describe the interaction between the matrix and the microstructure. We =96.64 (impact velocity 8 Åm / ps). The simulation results show that when the droplet spreads to its maximum diameter (25 nm), the composite microstructure forms a "multi-point puncture" effect, the diffusion velocity of the inner contact line of the annular liquid film reaches 1.8 nm / ps, and the contact time is 31 ps, which is 3.1% shorter than that of the single groove microstructure.

[0058] Example 3 (Different) D Research on the impact of value on rebound pattern Taking groove microstructure as an example ( Figure 1 ),fixed We =96.64, change D 2. (Groove length / droplet radius), observe the changes in the bounce pattern: D 2=0.2 (groove length 1nm): After the droplet spreads, it cannot form a stable ring structure, and presents a ring deposition. The contact time is 68ps, and the thickness of the residual liquid film on the surface is 0.5nm. D 2=0.6 (groove length 3nm): Stable annular rebound, contact time 32ps, no liquid film residue; D 2=1.2 (groove length 6nm): When the droplet spreads, it splits and splashes back, producing 3~5 sub-droplets (diameter 2~4nm). Some sub-droplets attach to the gaps in the microstructure, with a contact time of 45ps.

[0059] This result validates... D The optimal range for the cyclic rebound is 2 = 0.4~1.0. Figure 4 The phase diagram conclusions are consistent.

[0060] Therefore, the core mechanism by which this invention achieves low droplet adhesion and high insulation performance lies in "circular rebound-mediated contact time regulation." Combined with atomic-scale observations from molecular dynamics simulations, the specific mechanism is as follows: 1. The piercing effect and energy conversion of microstructures: When a droplet impacts the surface of a microstructure, the tip of the nanoscale microstructure pierces the liquid film, creating a local high-pressure zone (pressure ≥100 MPa), which causes the liquid film to reconstruct from a "disc-like" to a "ring-like" shape. During this process, the surface energy of the liquid film (approximately 1.2 × 10⁻⁶) decreases. - ¹ 5 J) is rapidly converted into upward kinetic energy (conversion efficiency ≥60%), allowing the droplet to rebound directly after spreading without going through the traditional retraction stage, shortening the contact time by 31%~37% compared to a flat surface.

[0061] 2. Insulation enhancement effect of the gas film: The air film (0.2~0.5nm thick) captured by the groove microstructure forms an "insulating buffer layer," which on the one hand prevents direct contact between the droplet and the substrate, reducing interfacial charge transfer; on the other hand, the low dielectric constant of the gas film ( e =1.0005) reduces the surface equivalent dielectric constant by 15%~20%, suppressing electric field distortion. Experiments show that in the presence of a gas film, the local field strength at the droplet edge decreases from 3.2 times the average field strength to 1.8 times, and the partial discharge initiation voltage increases by more than 60%.

[0062] 3. Synergistic regulation of microstructure spacing: spacing < 0.5 D max The design ensures that the droplet contacts multiple microstructures upon impact, creating a "multi-point support" effect and preventing prolonged local contact time caused by droplet tilting due to gravity. Molecular dynamics simulations show that when the spacing is 0.5... D ma At time x, the number of contact points between the droplet and the microstructure is ≥3, and the diffusion velocity along the contact line is greater than that at a spacing of 0.6. D max Increased by 25% in time.

[0063] Figure 2 This image shows a snapshot classification of five phenomena observed when droplets impact three different microstructure surfaces at different Weber numbers, with the images fixed. D 1. D 2. D The value for 3 is 0.6, respectively in We A standard rebound occurred at 24.16. We A cyclical rebound occurred at 96.64. WeSplash bounce occurs at a contact time of 151. The contact time of the standard bounce is not significantly different from that of the droplet impacting the flat surface. During the entire impact-bounce process at the top of the microstructure, trace amounts of water vapor or contaminants adsorbed on the surface are difficult to completely detach with the droplet. Some residual components remain attached to the gaps in the microstructure or the top surface, failing to completely eliminate potential pathways for interfacial charge conduction. The ring-shaped bounce and splash bounce modes are important findings in this experiment regarding reducing contact time, which plays a crucial role in enhancing surface insulation performance. First, a shorter contact time effectively prevents the formation of stable conductive paths. When the contact time between the droplet and the insulating surface is too long, continuous conductive paths may form on the surface, leading to current leakage. This invention significantly reduces this situation by reducing the contact time, thereby reducing instantaneous leakage current. Experimental data shows that using the microstructure insulating surface of this invention can reduce instantaneous leakage current by more than 60%. Secondly, reducing droplet contact time minimizes the residue of contaminants or electrolytes on the surface. These residues reduce the resistance of the insulating surface and increase the risk of leakage. This invention maintains long-term surface cleanliness and high insulation resistance. Furthermore, limiting water molecule adsorption on the surface is also crucial for enhancing insulation performance. Water molecule adsorption affects the bulk dielectric properties. This invention reduces water molecule adsorption by decreasing contact time, protecting the bulk dielectric properties and further enhancing surface insulation. In this state, droplet contact time can be effectively reduced, thus effectively suppressing the negative impact of nanodroplets on the insulation of the insulating coating. However, after splashing and rebounding, the droplet splits into multiple sub-droplets, and the rebound process of these sub-droplets is difficult to completely control. Some sub-droplets adhere to the solid surface, not only promoting the formation of surface conductive pathways but also indirectly damaging the bulk dielectric properties of the material, ultimately leading to a decrease in surface insulation. Therefore, splashing and rebounding is significantly less effective than ring-shaped rebounding in enhancing or maintaining the insulation of solid surfaces.

[0064] like Figure 3 As shown, we take We Droplets with a contact time of 96.64 were impacted on flat surfaces and three different microstructure surfaces, and their rebound processes were compared. The results showed that the contact time when the droplet impacted the flat surface was 70 ps, ​​while the contact time when impacting the microstructure surface was approximately 25-28 ps. This demonstrates that the contact time reduction rate during annular rebound is as high as 60% or more. The mechanism by which annular rebound achieves a significant reduction in contact time can be combined with... Figure 3The analysis is as follows: When a droplet impacts a flat surface, it undergoes two phases: spreading and retraction, with the retraction phase lasting significantly longer than the spreading phase. However, when a droplet impacts a particle surface, it rebounds in a ring shape without retraction, which is the key reason for the significantly shortened contact time. Specifically, when the droplet spreads to its maximum diameter, the particle punctures the center of the droplet, causing the inner contact line of the ring-shaped droplet to rapidly diffuse outward and approach the outer contact line. Its surface energy is then quickly converted into upward kinetic energy, driving the droplet to bounce off the solid surface in a ring shape, thus significantly reducing the contact time.

[0065] like Figure 4 We~D As shown in the phase diagram, the final determination is when D 2. Within the range of greater than 0.4 and less than 1, as the impact Weber number increases, the droplet will bounce off the contact surface in a ring-shaped manner. The diameter of small droplets in the air is between 10-100 nm. In order to achieve the full range of small droplet bounce, the overall length of the groove microstructure is determined to be within the range of 4-10 nm. The microstructure size can be customized according to the humidity of the environment where the device is located. That is, when the humidity is low, a "concave" shape microstructure size closer to 4 nm is selected, and when the humidity is high, a "concave" shape microstructure size closer to 10 nm is selected.

[0066] To ensure that the droplet inevitably comes into contact with the microstructure when it impacts the microstructure surface, we must maintain the spacing between each type of microstructure. d <0.5 D max ,in d Interparticle spacing, D Where is the droplet diameter, D max The maximum spreading diameter of the droplet. This ensures that the contact time is reduced to varying degrees when the droplet impacts the surface of the microstructure.

[0067] This invention precisely optimizes nanoscale microstructure parameters through molecular dynamics simulations, locking the annular rebound ranges of three microstructures: spherical, conical, and grooved. A superhydrophobic insulating surface is then fabricated using a "nanoimprinting + vapor deposition" process. This surface achieves performance indicators such as a static contact angle ≥150°, a droplet contact time reduction of over 60%, and an insulation strength ≥20kV / mm, with a performance degradation rate ≤10% after 3 years of environmental aging. Its core innovation lies in establishing a quantitative correlation model of "microstructure parameters-rebound mode-insulation performance," revealing the contact time regulation mechanism mediated by annular rebound, and overcoming the shortcomings of traditional technologies such as poor environmental stability and low regulation precision. This method can be widely applied in high-voltage power, new energy, and electronic packaging fields, providing new theoretical and technical support for the design of insulating surfaces in complex environments.

[0068] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A superhydrophobic insulating coating with a surface microstructure, characterized in that, It includes a superhydrophobic insulating substrate and microstructures modified on the surface of the superhydrophobic insulating substrate; the microstructures are one or more of the following: spherical microstructures with a diameter of 2-20 nm, grooved microstructures with a bottom length of 2-10 nm, or conical microstructures with a bottom diameter of 4-20 nm.

2. The superhydrophobic insulating coating with surface microstructure according to claim 1, characterized in that, The spacing between the microstructures is less than 0.5 times the maximum spreading diameter of the droplets on the flat surface of the superhydrophobic insulating substrate; the droplets are nanoscale droplets with a diameter of 10-100 nm.

3. The superhydrophobic insulating coating with surface microstructure according to claim 2, characterized in that, The spacing of the microstructures is 10-100 nm.

4. The superhydrophobic insulating coating with surface microstructure according to claim 1, characterized in that, The overall thickness of the coating is 50-200 nm, wherein the ratio of the height of the microstructure to the thickness of the superhydrophobic insulating substrate is 1:3-1:12.

5.

5. The superhydrophobic insulating coating with surface microstructure according to claim 1, characterized in that, The groove depth of the groove microstructure is 2-6 nm and the groove width is 2-10 nm, and the cone tip angle of the conical microstructure is 30°-120°.

6. The method for preparing a superhydrophobic insulating coating with surface microstructure as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) An initial molecular dynamics simulation system was constructed using nanoscale droplets with a diameter of 10-100 nm and an insulating matrix with one or more microstructure prototypes such as spheres, grooves or cones pre-modified on the surface. The interatomic interactions were defined using the Lennard-Jones force field. (2) Set the droplet impact velocity to 1-12 Åm / ps, simulate the impact process of nanodroplets on the microstructure surface within this velocity range, and record the curves of spreading diameter and contact angle changing with time; (3) Change the characteristic size of each microstructure and measure the ratio of the size of each microstructure to the droplet diameter. Δ Simulate different Δ Impact process under certain conditions; (4) Based on the droplet bounce mode under the microstructure, the droplet with the best hydrophobicity was preliminarily screened. Δ Value range; (5) For different Δ The droplet dynamics behavior under the specified value was quantitatively analyzed, the contact time between the droplet and the coating surface was calculated, and the contact time was compared with that of the droplet impacting the flat surface of the superhydrophobic insulating substrate. (6) Select the droplet with the shortest contact time and the complete bounce mode. Δ The value is used as the optimal size parameter. The maximum spreading diameter when nanoscale droplets impact a flat surface is used as the benchmark to determine the microstructure spacing, so that the spacing is <0.5 times the maximum spreading diameter. (7) Based on the simulation optimization parameters, the target microstructure is prepared on the surface of the superhydrophobic insulating substrate by nanoimprinting or vapor deposition to obtain the superhydrophobic insulating coating.

7. The preparation method according to claim 6, characterized in that, In step (1), the initial molecular dynamics simulation system is controlled at 25°C and at standard atmospheric pressure, with a simulation time step of 2 fs.

8. The preparation method according to claim 6, characterized in that, In step (3) Δ 1. Δ 2. Δ The adjustment range for value 3 is 0.2-2.0, and the adjustment gradient is 0.

1. When the simulation shows the liquid film rapidly contracting and detaching from the surface, the corresponding value is recorded. Δ The value is used as the preferred parameter.

9. The preparation method according to claim 6, characterized in that, In step (5), the contact time is calculated by taking the time difference between the droplet's first contact with the surface and its complete detachment from the surface. Multiple simulations are performed and the average value is taken, with the error controlled within ±5%.

10. The application of the superhydrophobic insulating coating with surface microstructure as described in any one of claims 1-5, characterized in that, Applications in improving the surface insulation performance of electrical equipment.

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